Accurate count of input and output in a manufacturing process is one of the most critical items of management information. An input count for a cigarette-making machine is difficult to obtain, however, because of the nature of the process.
In the production step preceding the making machine, other apparatus form a continuous tobacco rod and feed it axially toward the making machine. Adjacent to the maker, the rod is cut into cigarette-size pieces and, moving as an axial stream, is fed into the making machine. Mechanical methods cannot be used to count the cigarettes here due to the high speed of operation (4000 pieces per minute or more) and the fragility of the product. Conventional photoelectric means were also tried, without success. Such methods depend on detecting the gaps between individual articles; here, the stream of cigarettes is being pushed from the rear, so no gap exists. Several methods were employed in an effort to induce a gap between articles. The most promising of these was to accelerate successive cigarettes forward, using a drum or other means. The cigarette diameter varies, however, within manufacturing tolerances, and it was found that, if the acceleration mechanism was set to handle the smaller articles, it deformed the larger ones; conversely, if set not to deform larger cigarettes, it failed to accelerate many of the smaller ones, resulting in unreliable counts.
Therefore, a need exists for a method of counting cigarettes being fed into the making machine. Such a method must not only be capable of operation within the given process parameters, but also it must be adaptable to the size and environmental constraints imposed by existing machinery.